Lamp assemblies including a generally concave shaped reflector are well-known for use in curing photoinitiated adhesives and other coating compositions.
UV radiation curing offers significant energy and savings versus thermal curing in heat ovens. UV radiation curing also is much quicker offering significant time savings, and is more environmentally friendly in reducing toxic emissions. Another advantage of UV curing is the adhesives leave behind no solvent residue, as is common with thermoplastic adhesives which set upon cooling or evaporation of a solvent. This is important in certain applications, e.g. medical device manufacturing, to avoid compromising biomedical acceptability.
Previously, lamp assemblies commercially available for UV curing included a lamp horizontally disposed and fixed at the time of manufacture in a reflector. These lamp assemblies were criticized as inefficient. A "Prefocused Lamp Reflector Assembly" was proposed in U.S. Pat. No. 5,387,800 issued to Dymax Corporation, and a similar lamp assembly is currently being sold by Dymax. That assembly provides for moving of the reflector and thereby manually focusing the radiation from the lamp by the user. Then the relative position of the reflector to the lamp is fixed by the user through use of a bonding material.
Although the Dymax lamp assembly has proven generally suitable for its intended purposes, it possesses numerous inherent deficiencies which detract from its overall effectiveness and desirability. During the focusing process the user is exposed to the UV radiation from the lamp assembly, and possible electric shock from the connections of the power source to the lamp. Touching the lamp or reflector leaves behind human skin oil, which may later adversely affect performance of the lamp assembly or cause the lamp or reflector to crack at the place where human skin oil resides.
After the Dymax lamp assembly is focused, the reflector is bonded to a thin sheet metal bracket with clips holding the lamp. As the bonding material solidifies over several hours, sometimes the reflector skews slightly which reduces the output from the lamp assembly. Once the bonding material has solidified, it is no longer possible to refocus the lamp assembly. The bonding material may also deteriorate over time, causing further problems.
Because only weak structure secures the lamp, sometimes there is arcing between the lamp and the bracket contacts. Additionally, the weak structure of the Dymax lamp assembly provides little protection for the fragile lamp and reflector, which are subject to breakage especially during shipping.
In view of the shortcomings of the prior art, it is an object of this invention to provide a lamp reflector assembly providing speedy and easy alignment of the reflector relative to the lamp, to mechanically focus the radiation output of the assembly.
It is a further object of this invention to provide a lamp reflector assembly with sufficiently strong structural framework to maintain indefinitely the position of the reflector and the lamp once focusing by the user is complete, and to protect the lamp and reflector during shipping.
It is still a further object of this invention to provide a lamp reflector assembly such that focusing can be completed without unduly exposing the user to UV radiation or electric shock, and without the user having to touch the lamp or reflector thereby depositing human skin oil.
Finally, it is yet another object of the present invention to fix the relative position of the reflector to the lamp without the use of bonding material.